The present invention relates generally to speed indicating systems and more particularly to apparatus for indicating the deviation of a motor from a standard speed. The present invention is particularly suitable for application to the drive mechanism of record playback systems.
In the conventional record players, stroboscopic methods are usually employed to indicate the deviation of turntable speed from a setting speed level. More specifically, the turntable is provided along its circumference with a number of concentric rings each containing a different number of dark and light segments. When the turntable is illuminated at a known frequency by a flashing discharge tube, speed can be determined by noting which pattern appears to be at a standstill or rotate slowly or fast. However, the conventional method is inappropriate for high-precision type record players where the speed deviation on the order of less than 1% is to be visually indicated. Furthermore, the stroboscopic pattern is blurred for a moment when the speed setting is changed until the turntable approaches the new setting level.